Reliable supplies of electric power have become an important aspect of many endeavors, and in some cases it is important to strive for as near to 100% availability as is possible. Examples include facilities supporting human health and safety such as hospitals and air traffic control, as well as core services such as telephone networks, computer data centers and financial exchanges. One technique for achieving high availability of electric power is to maintain access to multiple independent sources of electric power at a facility. For example, a computer data center may contract with multiple independent generators of electric power and have each provider run separate and independent transmission lines to the facility.
As part of managing multiple independent sources of electric power, many sites will configure one source of electric power to be primary and/or active, while other sources are secondary and/or backup. Electrical switching equipment may then be used to switch from the active source to the backup source as needed. However, such switching equipment can itself become a point of failure. In particular, some types of electrical relay components used to make and break electrical connections that are incorporated in switching equipment can be prone to failure, which can undermine even sophisticated high availability arrangements. For example, relays having metal armatures that physically move to make and break the electrical connection can spark while changing state degrading the relay and even causing relay failure. However, such relays may be preferred over alternatives such as solid state relays for other performance characteristics such as low resistance when closed, resulting in low amounts of electrical power being wasted as heat. The tradeoff between high availability and wasted energy can be a significant dilemma for designers of conventional high availability electric power systems.